WIP: Interactive SSP selection

This is the WIP on implementing https://github.com/mne-tools/mne-python/issues/380. Currently it's incorporating topomap plotting after https://github.com/mne-tools/mne-python/pull/392 (Thanks @agramfort). Individual components can be (de-)selected by clicking on them (indicating by white/red background color).

Code to run the current plot:

    import mne

    path = mne.datasets.sample.data_path()
    ev_file = path + '/MEG/sample/sample_audvis-ave.fif'
    subjects_dir = path + '/subjects'

    ev = mne.fiff.Evoked(ev_file, setno='Left Auditory')
    layout = mne.layouts.read_layout('Vectorview-all')

    p = mne.viz.gui_select_proj(ev, layout)

![Screen Shot 2013-01-22 at 5 37 19 PM](https://f.cloud.github.com/assets/145771/87843/027ce0d8-64d4-11e2-92f2-736d4e22d9fb.png)

To do:
* working with different sensor types. Simple options would be one topomap per sensor type. @agramfort suggested remapping all data to virtual magnetometers (https://github.com/mne-tools/mne-python/pull/392) can you provide a link to the matlab implementation?
* plot and update evoked  
* it might be useful to see for each component the time course in the average and in some single trials. How many components are we usually/maximally dealing with? Depending on that we might add them to the main plot or add some sort of pop-up on click functionality.